components (PCs), genotype array, and birth cohort as covariates. To adjust for familial clustering, we used cluster robust standard errors (Colin Cameron et al., 2011; Davenport et al., 2011). We stratified analyses by genetic similarity and then meta-analyzed results (by PGS) within each of the analyses above. All analyses were corrected for multiple testing. We also performed a GWAS of SA, but lacked the power to identify any individual variants associated with SA (see supplementary information)
